Don't forget to remove the "colour wash" surface paint used to give most of these models' plastic surfaces their patinated, plated or weathered effects. Just scrape oor abrade the areas where parts meet to clean off this paint. If you don't this "wash" can act as a barrier to or contaminate the adhesive you are using to bond parts together. This can lead to a poor bond and joints failing even with the secondary processes already suggested. If done properly a decent solvent based adhesive should be adequate on its own.
I have found Technicoll 8008 adhesive offers the strongest bonds with these kits' plastic.
Also, try to site buildings and structures away from positions in full sun to ensure maximum life without any failures. Constant cycles of heat induced expansion and contraction can lead even "welded" plastic joints to fail. Max